Change search
ReferencesLink to record
Permanent link

Direct link
Mechanisms for the Breakdown of Halomethanes through Reactions with Ground-State Cyano Radicals
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.
Hokkaido Univ, Dept Chem, Fac Sci, Kita Ku, Sapporo, Hokkaido 0600810, Japan.
Purdue Univ, Dept Chem, W Lafayette, IN 47907 USA.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Theoretical Chemistry.ORCID iD: 0000-0002-1312-1202
2015 (English)In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 16, no 1, 181-190 p.Article in journal (Refereed) Published
Abstract [en]

One route to break down halomethanes is through reactions with radical species. The capability of the artificial force-induced reaction algorithm to efficiently explore a large number of radical reaction pathways has been illustrated for reactions between haloalkanes (CX3Y; X=H, F; Y=Cl, Br) and ground-state (2Σ+) cyano radicals (CN). For CH3Cl+CN, 71 stationary points in eight different pathways have been located and, in agreement with experiment, the highest rate constant (108 s−1 M−1 at 298 K) is obtained for hydrogen abstraction. For CH3Br, the rate constants for hydrogen and halogen abstraction are similar (109 s−1 M−1), whereas replacing hydrogen with fluorine eliminates the hydrogen-abstraction route and decreases the rate constants for halogen abstraction by 2–3 orders of magnitude. The detailed mapping of stationary points allows accurate calculations of product distributions, and the encouraging rate constants should motivate future studies with other radicals.

Place, publisher, year, edition, pages
2015. Vol. 16, no 1, 181-190 p.
Keyword [en]
gas-phase reactions; quantum chemistry; radical reactions; reaction mechanisms; transition states
National Category
Theoretical Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-228448DOI: 10.1002/cphc.201402601ISI: 000347239200018PubMedID: 25263486OAI: oai:DiVA.org:uu-228448DiVA: diva2:734148
Funder
Marcus and Amalia Wallenberg FoundationSwedish Research CouncilSwedish National Infrastructure for Computing (SNIC), p2011004
Available from: 2014-07-15 Created: 2014-07-15 Last updated: 2016-11-08Bibliographically approved
In thesis
1. Theoretical Studies of Ground and Excited State Reactivity
Open this publication in new window or tab >>Theoretical Studies of Ground and Excited State Reactivity
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

To exemplify how theoretical chemistry can be applied to understand ground and excited state reactivity, four different chemical reactions have been modeled. The ground state chemical reactions are the simplest models in chemistry. To begin, a route to break down halomethanes through reactions with ground state cyano radical has been selected. Efficient explorations of the potential energy surfaces for these reactions have been carried out using the artificial force induced reaction algorithm. The large number of feasible pathways for reactions of this type, up to eleven, shows that these seemingly simple reactions can be quite complex. This exploration is followed by accurate quantum dynamics with reduced dimensionality for the reaction between Cland PH2Cl. The dynamics indicate that increasing the dimensionality of the model to at least two dimensions is a crucial step for an accurate calculation of the rate constant. After considering multiple pathways on a single potential energy surface, various feasible pathways on multiple surfaces have been investigated. As a prototype of these reactions, the thermal decomposition of a four-membered ring peroxide compound, called 1,2-dioxetane, which is the simplest model of chemi- and bioluminescence, has been studied. A detailed description of this model at the molecular level can give rise to a unified understanding of more complex chemiluminescence mechanisms. The results provide further details on the mechanisms and allow to rationalize the high ratio of triplet to singlet dissociation products. Finally, a thermal decomposition of another dioxetane-like compound, called Dewar dioxetane, has been investigated. This study allows to understand the effect of conjugated double bonds adjacent to the dioxetane moiety in the chemiluminescence mechanism of dioxetane. Our studies illustrate that no matter how complex a system is, theoretical chemistry can give a level of insight into chemical processes that cannot be obtained from other methods.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2014. 86 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1179
Keyword
Chemical Reactivity, Computational Chemistry, Dynamics, Ground and Excited States, Chemiluminescence, Atmospheric Chemistry
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-232219 (URN)978-91-554-9036-2 (ISBN)
Public defence
2014-10-30, Häggsalen, Ångström laboratory, Uppsala, 13:00 (English)
Opponent
Supervisors
Available from: 2014-10-09 Created: 2014-09-15 Last updated: 2015-01-23Bibliographically approved
2. Theoretical Studies of Seemingly Simple Chemical Reactions
Open this publication in new window or tab >>Theoretical Studies of Seemingly Simple Chemical Reactions
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Place, publisher, year, edition, pages
Uppsala universitet, 2013. 38 p.
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-228291 (URN)
Presentation
2013-12-11, Å80101, Uppsala University, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2014-07-15 Created: 2014-07-09 Last updated: 2015-03-24Bibliographically approved

Open Access in DiVA

fulltext(1681 kB)13 downloads
File information
File name FULLTEXT01.pdfFile size 1681 kBChecksum SHA-512
a9c6b28d374c39f41242a7170d84d3db3cf95d6efb9beb92598fbdaf31a57e366d9579b580e732d2016e61a695e7f62e091ba45439f6eeda1de8685d24beb5ff
Type fulltextMimetype application/pdf

Other links

Publisher's full textPubMed

Search in DiVA

By author/editor
Farahani, PooriaLundberg, Marcus
By organisation
Theoretical Chemistry
In the same journal
ChemPhysChem
Theoretical Chemistry

Search outside of DiVA

GoogleGoogle Scholar
Total: 13 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 461 hits
ReferencesLink to record
Permanent link

Direct link